Erin Moran's husband has revealed she passed away holding his hand while watching TV in bed.

In an open letter on Facebook, Steven Fleischmann described how the 56-year-old Happy Days star discovered she was sick in November 2016 after returning from celebrating their 24th wedding anniversary.

"Erin woke up and had about a dime sized blood stain on her pillowcase," Steven wrote in a post shared by the Happy Days actress' co-star Scott Baio. "She said 'I think I bit my tongue'. A couple days go by and there's a bigger spot of blood."

Suspecting tonsillitis, Erin then visited an Ear Nose and Throat doctor where she discovered she had squamous cell carcinoma, a common form of skin cancer. She then started radiation five days a week and chemotherapy every Thursday.

"We did that the whole time," Steven recalled. "It got so bad so fast. By the middle of February, Erin could no longer speak or eat or drink.

"She had a feeding tube implant and I feed her 6 to 8 times a day. She was still happy, she was active, she texted people on her phone all day."

On April 21st, the day before she died, Erin was having trouble breathing.

"She woke up on the 22nd, she was not 100 per cent," Steven explained. "She needed Kleenex, so I went to the store and came back.

"She was there watching TV in bed. I laid down next to her held her right hand in my left. I feel asleep woke up about an hour later still holding her hand and she was gone, she was just gone."

It was only after Erin's death that Steven learnt how far the cancer had spread.

"The coroner told me it was really, really bad," Steven wrote. "It had spread to her spleen, she had a lot of fluid in her lungs and part of her brain was infected. The coroner said even if she was in the hospital being pumped full of antibiotics she still would not have made it.

"He said it was the best that she was with me and went in her sleep."

While some speculated that Erin's alleged history of drugs and alcohol was the cause of death, the Harrison County Sheriff’s Office confirmed that she died from complications of Stage 4 cancer.